Currently, automotive bodies are made from sheet steel and/or polymer composites. They typically consist of 150 to 200 parts of varying complexity which are fabricated and then joined together to form the assembled body. The sheet metal parts are usually stamped and the polymer panels are molded. A large number of separate components are required because of current material and manufacturing limitations. However, joining these parts requires tabs, flanges and fixturing which increase their complexity and cost. Also, joints are a potential source of quality problems such as poor fit and finish, squeaks and rattles.
Body manufacturing costs for tools, assembly fixtures and facilities are directly related to the number of parts required to make the body. Hence, to reduce cost and increase quality, the number of body parts and joints should be reduced.